The present invention relates to a width reducing installation of hot slabs and, more particularly, to a slab sizing press which reduces the width of a slab by pressing the slab side surfaces by reciprocatively driving caused by rotation of opposite crank shafts.
In a conventional slab sizing press, a method of connecting a crank shaft and an outer block by connecting rods each having bearings at both ends thereof (JP B 2-50807, FIG. 3) or a method of connecting them by connecting rods each having a bearing on the crank shaft side and formed in a male-female spherical surface (pitman) on the outer block side (JP A 5-123701, FIG. 4) is realized as a means for transmitting reciprocatively driving caused by rotation of the crank shaft to the outer block.
As required commonly to industrial machinery, it is required also for a slab sizing press installation to be low in installation cost, simple in construction and excellent in maintainability. In the slab sizing press, slab side surfaces are pressed by using dies each having a parallel portion and a tapered portion to obtain a desired slab width. In this case, in order to prevent buckling or to control flatness shape of the slab, leading and trailing ends of the slab are preformed and the slab is reversely pressed depending on forward and backward equipments.
The center of a press load in the slab sizing press changes according to such a die shape and various operation modes and, particularly, a large change in an entry-delivery direction becomes a cause of destroying the
The conventional slab sizing press disclosed in the JP B 2-50807 is provided with bearings at both ends of 2 connecting rods arranged on each side of entry and delivery sides, that is, 4 connecting rods in total. The slab sizing press has a high mechanical stability to a change of the press load center, however, a equipment cost is high because the construction is complicate and maintainability therefor is bad.
Further, the slab sizing press disclosed in the JP A 5-123701 is provided with one connecting rod on each side, that is, 2 connecting rods in total, each connecting rod is formed in a male-female spherical surface (pitman) on the outer block side and a crank mechanism is relatively simple. However, since it is connected by one connecting rod, the mechanism such as the press load center changes is low in stability, and angular moment due to deviation of the load center occurs on the outer block. Therefore, it is necessary to provide a guide mechanism which can resist the angular moment on a peripheral portion of the outer block, and the maintainability of the guide mechanism is bad. Further, the male-female spherical surface portions are in slipping contact with each other and wear, so that the maintainability also is bad from this point of view.
Because of the presence of the above-mentioned problems, there is desired a slab sizing press which has both a highly stable mechanism and a simple construction, and which is excellent in maintainability.
An object of the present invention is to provide a slab sizing press which is mechanically stable, simple in construction and excellent in maintainability.
(1) In order to attain the above-mentioned object, the present invention comprises an eccentric crank shaft, an arm rotatably mounted on the eccentric crank shaft, a first block transmitting a load between the arm, a second block mounted so that a distance from the first block is adjustable and a die mounted on the second block, has a first rolling element provided on one side of a load transmission portion between the arm and the first block and a second rolling element provided on the other side of the load transmission portion, wherein a load is transmitted by rolling contact between the first rolling element and second rolling element, and gears, as means for preventing the first and second rolling elements from slipping on rolling contact surfaces, provided on the sides of the arm and the first block so as to mesh with each other, and movably supports at least one of the gears.
By providing the first rolling element on one side of the load transmission portion between the arm and the first block to transmit a load by rolling contact therebetween, the facility construction is made simple and the length of the facility can be reduced, without necessity of conventional connecting rods.
Further, by providing the gears which mesh with each other on both the arm side and the first block side as a slip prevention means of the rolling contact surfaces of the first and second rolling elements, it is possible to keep a load transmission course constant and to obtain a high mechanical stability. At the same time, it is possible to suppress the wear of the rolling contact surfaces and to improve the maintainability of the equipment.
The above-mentioned matter is based on the technical idea of the invention proposed in JP A 9-299914 which is an earlier Japanese application of the corresponding Japanese application.
In the present invention, in addition to the above, at least one of the gears meshed with each other is movably supported, whereby even if elastic deformation occurs on the rolling surfaces of the first and second rolling elements, the gears are not pressed on each other, so that any wedge effect does not occur. Therefore, it is possible to avoid an excessive surface pressure or bending stress, acting on the tooth surfaces, to make the gear life long, and to further improve the maintainability of the equipment.
(2) In the above-mentioned item (1), preferably, a stopper for limiting a movement range of the gear and a means for urging the gear to press on the stopper are provided as a means for holding the movably supported gear at a desired position.
By pressing the movably supported gear on the stopper with force larger than the inertia acting on the gear by reciprocative driving, it is possible to exclude an influence of the inertia, so that a relative position of the first and second rolling elements can be held with high precision and it is possible to make the life further long.
(3) Further, in the above-mentioned item (2), preferably, a third rolling element moving integrated with the movably supported gear is provided as means for maintaining a distance between the meshing gears, the third rolling element is made in the same shape as a rolling surface of the rolling element on the side of the movably supported gear, and contacted with the rolling element on the side of the other gear.
Thereby, a distance between the meshed gears can be kept constant, so that a desired backlash can be held, the wedge effect and sticking of tooth faces can be suppressed and further long life of the gears can be realized.